Storm as Wide as Earth Rages on Saturn

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The Great White Spot on Saturn has been imaged in unprecedented
detail and is now yielding clues to how this titanic storm may
have formed far earlier than scientists expected.

The staggeringly powerful thunderstorm is approximately 6,200
miles (10,000 kilometers) wide, nearly as wide as Earth, and has
a tail of white clouds that encircles all of Saturn.

The storm began forming in the ringed planet's northern
hemisphere in December. This is about 10 years early for
Great White Spots, which usually recur about every 30 Earth
years, when Saturn's northern hemisphere tilts most toward the
sun.

Only five similar Great White Spots have been observed in the
past 135 years.

To learn more about this mystery storm, researchers employed both
ground-based telescopes and observations from the Cassini
spacecraft in orbit around Saturn. Their findings show it to
be packing as much total energy as "the Earth receives from the
sun within one year," said researcher Georg Fischer, a planetary
scientist at the Austrian Academy of Sciences in Graz. [ Photos:
Rings and Moons of Saturn ]

The Great White Spot is a
massive complex of thunderstorms. Radio waves emitted by
electrical discharges there reveal intense and nearly continuous
lightning that, at the peak of the storm, can flash 10 times or
more per second.

A key mystery regarding Great White Spots is where they get their
energy from. Since the spots seem to occur seasonally,
researchers had suggested they might be powered by the sun.
However, peering into this latest Great White Spot revealed its
cloud patterns make sense only if winds "extend deep into the
'weather layer' — a 250-kilometer-thick [155 miles] layer where
the main clouds reside, where sunlight does not arrive,"
researcher Agustin Sánchez-Lavega, a planetary scientist at
Higher Technical School of Engineering of Bilbao in Spain, told
SPACE.com. "This points to the action of an internal heat source
as the power for the winds."

Still, questions remain as to how solar heat might help trigger
such gigantic storms. One possibility is that energy from the sun
triggers atmospheric changes that directly influence the upward
flow of heat from deep within Saturn, researchers say.

The researchers detailed their findings in the July 7 issue of
the journal Nature.

Follow SPACE.com contributor Charles Q. Choi on Twitter @cqchoi. Visit
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